Tissues
NCERT Solutions • Class 9 Science • Chapter 6Chapter Exercises
1. Define the term “tissue”.
A tissue is a group of cells that are similar in structure and/or work together to achieve a particular function. Examples include blood, phloem, and muscle.
2. How many types of elements together make up the xylem tissue? Name them.
Xylem is a complex tissue made up of four types of elements:
1. Tracheids
2. Vessels
3. Xylem Parenchyma
4. Xylem Fibres
1. Tracheids
2. Vessels
3. Xylem Parenchyma
4. Xylem Fibres
3. How are simple tissues different from complex tissues in plants?
| Feature | Simple Tissues | Complex Tissues |
|---|---|---|
| Cell Type | Made of only one type of cells. | Made of more than one type of cells. |
| Examples | Parenchyma, Collenchyma, Sclerenchyma. | Xylem, Phloem. |
4. Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.
| Parenchyma | Collenchyma | Sclerenchyma |
|---|---|---|
| Primary cell wall is thin. | Primary cell wall is irregularly thickened at corners. | Secondary cell wall is thick and lignified (contains lignin). |
| Made of Cellulose. | Made of Cellulose and Pectin. | Made of Lignin. |
[Image of open and closed stomata structure]
5. What are the functions of the stomata?
Functions of Stomata:
1. Gas Exchange: They allow for the exchange of gases (CO₂ and O₂) with the atmosphere during photosynthesis and respiration.
2. Transpiration: They help in the loss of excess water in the form of water vapour, which also aids in the upward movement of water.
1. Gas Exchange: They allow for the exchange of gases (CO₂ and O₂) with the atmosphere during photosynthesis and respiration.
2. Transpiration: They help in the loss of excess water in the form of water vapour, which also aids in the upward movement of water.
[Image of striated smooth and cardiac muscle tissues diagram]
6. Diagrammatically show the difference between the three types of muscle fibres.
(Refer to the diagram above showing Striated, Smooth, and Cardiac muscles)
• Striated: Cylindrical, multinucleate, with bands.
• Smooth: Spindle-shaped, uninucleate, no bands.
• Cardiac: Cylindrical, branched, uninucleate, with faint bands.
• Striated: Cylindrical, multinucleate, with bands.
• Smooth: Spindle-shaped, uninucleate, no bands.
• Cardiac: Cylindrical, branched, uninucleate, with faint bands.
7. What is the specific function of the cardiac muscle?
Cardiac muscles are present only in the heart. Their specific function is to undergo rhythmic contraction and relaxation throughout life without getting fatigued, enabling the heart to pump blood to all parts of the body.
8. Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.
| Feature | Striated (Skeletal) | Unstriated (Smooth) | Cardiac |
|---|---|---|---|
| Structure | Cylindrical, unbranched, multinucleate, light/dark bands. | Spindle-shaped, unbranched, uninucleate, no bands. | Cylindrical, branched, uninucleate, faint bands. |
| Location | Attached to bones (Limbs). | Iris of eye, Ureters, Bronchi, Alimentary canal. | Walls of the Heart. |
[Image of neuron labelled diagram]
9. Draw a labelled diagram of a neuron.
(Diagram showing Cell Body, Nucleus, Dendrites, Axon, and Nerve Ending)
A neuron consists of a cell body with a nucleus and cytoplasm, from which long thin hair-like parts arise (Dendrites and Axon).
A neuron consists of a cell body with a nucleus and cytoplasm, from which long thin hair-like parts arise (Dendrites and Axon).
10. Name the following.
- (a) Inner lining of mouth: Squamous Epithelium
- (b) Connects muscle to bone: Tendon
- (c) Transports food in plants: Phloem
- (d) Stores fat in body: Adipose Tissue
- (e) Connective tissue with fluid matrix: Blood
- (f) Tissue present in brain: Nervous Tissue
11. Identify the type of tissue in the following: skin, bark of tree, bone, lining of kidney tubule, vascular bundle.
• Skin: Stratified squamous epithelium.
• Bark of tree: Cork (Protective tissue).
• Bone: Connective tissue.
• Lining of kidney tubule: Cuboidal epithelium.
• Vascular bundle: Complex permanent tissue (Xylem and Phloem).
• Bark of tree: Cork (Protective tissue).
• Bone: Connective tissue.
• Lining of kidney tubule: Cuboidal epithelium.
• Vascular bundle: Complex permanent tissue (Xylem and Phloem).
12. Name the regions in which parenchyma tissue is present.
Parenchyma is the most common simple permanent tissue. It is present in the cortex and pith of stems and roots, as well as in the mesophyll of leaves. It is also found in the soft parts of fruits and flowers.
13. What is the role of epidermis in plants?
1. Protection: It protects all parts of the plant against loss of water, mechanical injury, and invasion by parasitic fungi.
2. Water Conservation: In dry habitats, it has a thick waxy coating of cutin to prevent water loss.
3. Gas Exchange: Through stomata present in leaf epidermis.
4. Absorption: Root epidermal cells have hair-like parts to increase surface area for water absorption.
2. Water Conservation: In dry habitats, it has a thick waxy coating of cutin to prevent water loss.
3. Gas Exchange: Through stomata present in leaf epidermis.
4. Absorption: Root epidermal cells have hair-like parts to increase surface area for water absorption.
14. How does the cork act as a protective tissue?
Cork cells are dead and compactly arranged without intercellular spaces. They have a chemical substance called suberin in their walls that makes them impervious to gases and water, thus protecting the underlying tissues from desiccation, infection, and mechanical injury.
15. Complete the following chart (Permanent Tissues):
-
Permanent Tissue
-
Simple
- Parenchyma
- Collenchyma
- Sclerenchyma
-
Complex
- Xylem
- Phloem
-
Simple